In the development of new medicines or medical basic research, biological samples, such as sperms, fertilized ova, and cells of laboratory animals, are used. Since biological samples deteriorate due to a biological action at normal temperature, it is general that the biological samples are cryopreserved by cryopreservation devices or the like. Since cryopreservation devices using liquid nitrogen can stably maintain biological samples for a long period of time, these cryopreservation devices have been widely used.
For example, Patent Literature 1 discloses a cryopreservation device that has an opening with about half the diameter of a vessel and can freely rotate an internal placement tray, as one of the cryopreservation devices using liquid nitrogen. In addition, in the cryopreservation vessel disclosed in Patent Literature 1, in order to store samples in large quantities, a plurality of samples are stored in a storage box, and a plurality of the storage boxes are stored in a case main body.